Christchurch residents will have to restrict their water use from Monday while the city council works on making wells safe from contamination.
Gardens can only be watered every second day, and only by hand.
Those living at even numbered addresses can water on even numbered dates, while those at odd numbered addresses will be able to do so on odd numbered dates.
The restrictions will apply from March until May.
In the meantime, chlorine will continue to be used to prevent ground wellheads from becoming contaminated, especially during heavy flooding.
Ninety percent of wells will have the chlorine removed by May, but treatment will continue until October for suburbs including Beckenham, Cashmere, Spreydon and Ōpāwa.